Well, you can't say they sneak it in. From the opening frames, there it is- American blackface in all its cheerful glory. Eddie Cantor was known for this sort of thing, and he's the producer of this post-war epic. Even so, by the time of the film's release, blackface minstrelsy was dying out amidst organized protests against these grotesque racial caricatures. The civil rights era was dawning, though segregation was still the law in much of the country, and an informal Jim Crow reigned throughout the whole 48. Incidentally, in the opening number, the chorus girls are made up and given wigs that seem designed to remind the viewer of Lena Horne. She would have despised the film on that basis alone, while reserving a full portion of contempt for the persistence of blackface in the contemporary era.